Sack-filling device

ABSTRACT

A sack-filling device is provided for filling particulate material into sacks having a sack valve without entrainment of air in the filled sack, permitting air within the sack to vent while preventing entry of outside air, comprising a sack-filling means, and a sealing insert having a wide end and a narrow end, adapted to sealingly engage the sack-filling means at the narrow end, and sealingly engage the inside of a sack valve at the wide end, to substantially close off the sack valve during filling of the sack.

United States Patent Forssen et al. June 3, 1975 1 SACK-FILLING DEVICE3,1 12,32 H3221 $561116 ill/1319146)? 3,1 't [751 Inventors: Fmse";Lindius, both of 3,261,379 71966 StOlfel 141/68 x Malmov Sweden3,265,098 8/1966 011661 141/68 x Assigneez Aktiebolaget Cementa, Malmo3,294,127 Lau X Sweden [22] F] d J 24 1971 Przmary ExammerW. A. Morse,Jr.

1 e une 21 App]. No.: 156,497 1 1 ABSTRACT A sack-filling device isprovided for filling particulate [52] U S Cl 141/68. 141/292. IAN/315material into sacks having a sack valve without en- [51] B651) 1/18.B65b 1/28. trainment of air in the filled sack, permitting air withinB65b 3/17.B65b the sack to vent while preventing entry of outside air,[58] Field of Search 141/68 315 292 comprising a sack-filling means, anda sealing insert a having a wide end and a narrow end, adapted to seal-[56] References Cited ingly engage the sack-filling means at the narrowend, and sealingly engage the inside of a sack valve at the UNITEDSTATES PATENTS wide end, to substantially close off the sack valve dur-2,046,761 7/1936 Andreas 141/68 in n of the Sack 2,058,118 10/1936 White141/392 g g 2,412,026 12 1946 Adams 141/68 5 Cla1ms,3 Drawmg Flgures I ll l IrIIIIIIIJ IIIIIIIIIIIIII 1 SACK-FILLING DEVICE pulverizedmaterials, such as cement, plaster and bydrated lime, are mainly filledinto valve sacks by semiautomatic filling machines. Hand-filling ofsacks and the sewing of the sack openings after filling are not used anymore, because of high labor costs. Instead, the sacks are designed withan opening provided with an internally-extending baffie or tube,referred to as a sack valve, adapted to receive the filling tube of anautomatic filling machine. The filling machine normally includes ahopper adequate to retain a supply of the particulate material, and thematerial is fed from the hopper through the filling tube into the sack.

In the course of transport of the particulate material to the hopper, aconsiderable amount of air may be entrained with the material. In thecase of cement, for example, the density of the material measured in thehopper of a filling machine is within the range from 1.1 to 1.3, whilein a large silo or the like, after the material has been allowed tosettle for a day or so, the density will have risen to from 1.3 to 1.5.This air is of course fed into the sack with the material, and must bevented from the sack, if possible, in order to obtain the rated weightof material in the filled sack.

One type of semiautomatic filling machine is known as a tube packer. Inthis apparatus, a rapidly rotating turbine wheel is used to transportthe particulate material, such as cement, from the hopper through thefilling tube into the sack. In this case, the sack opening is fastenedaround the tube. Due to the design of the tube, and the loose fit of thesack valve, air which enters the tube together with the particulatematerial can leave the sack through a channel formed under the tube,inasmuch as the outside diameter of the tube is smaller than the sackopening or the sack valve.

In filling sacks with this kind of device, the sack becomes taut as itis being filled, and increases in weight with the weight of thematerial, and the resulting change in internal volume of the sack causesair to be drawn into the sack during the first few seconds of thefilling process. This air also mustbe removed from the sack at a laterstage of the filling, to ensure that full weight of the sack isobtained, or alternatively a sack must be used that is of excessivelylarge volume, to provide for both the given rated weight of particulatematerial and the air.

On some types of filling machines, the filling tube is fitted with anexpandable collar, which opens out after the sack has been fitted to thetube, and before the particulate material begins to enter the sack. Thiscollar helps to reduce the amount of air drawn in, but it cannot bedesigned to make a tight seal if the air that has entered with thematerial is to be allowed to escape from the sack towards the end of thefilling process.

In accordance with the invention, a sack-filling device is provided forfilling particulate material into sacks having a sack valve, withoutentrainment of air in the filled sack and which permits air within thesack to vent, while preventing entry of outside air. This sackfillingdevice comprises, in combination, a sack-filling means smaller indiameter than the inside diameter of the sack valve, and adapted toextend into the sack valve of the sack, to feed, particulate materialthereinto, and a sealing insert having a wide end and a narrow end, andto sealingly engage the inside of the sack valve at the wide end,substantially closing off the sack valve, the insert being sufficientlyresilient to flex away from the sack-filling tube and open the sealtherewith for egress of gas such as air within the sack when under highgas pressure therewithin or under the stress applied to the insert bythe sack under the weight of particulate material filled therein.

In a preferred embodiment of sealing insert, the insert is in the formof a truncated cone, mounted on the filling tube in a manner such thatthe narrow end of the cone points toward the inside of the sack, whilethe outer periphery of its wide end fits closely against the inner wallof the sack valve. The insert can however have any externalconfiguration, as may be convenient to seal with the sack valve, such aselliptical, round, or polygonal (such as triangular, square,rectangular, and hexagonal), in a sloping or tapered form, straight orcurved, convexly or concavely. The sealing insert, such as the truncatedcone, is made of a material that is sufficiently rigid to open out thesack valve when the sack is empty, and keep it open while sealinglyengaging the interior walls thereof during the first stage of thefilling process, so that ingress of air during this stage is prevented.However, the material, at least at the narrow end, should besufficiently resilient so that it yields to the gas pressure that buildsup in the sack toward the end of the filling process, and enables thegas such as air within the sack to escape past the insert. The insertshould also be capable of yielding when the weight of the material inthe sack is so great that the sack valve is forced by the load to assumea different shape. In either case, either the wide end, or the narrowend, or both, of the sealing insert become distorted, and break thesealing engagement with the sack valve and/or with the filling tube,allowing the gas such as air to pass the insert, and escape from thesack.

The sealing insert may be permanently attached to the filling tube, orit may be permanently attached to the sack valve, It may also beremovably attached to either'the filling tube or the sack valve, foreasy replacement in case of damage or wear.

In the event that the sealing insert is in the form of a truncatedconical or tapered tube, fitted in the sack, its larger diameter facesoutward, so that the sack can be easily fitted over the insert and thefilling tube of the filling machine. If the insert is fixedly attachedto the walls of the sack valve, it is unattached at the end fitting overthe filling means, and attached only at certain points to the sack valvewalls, so that air will be able to escape therebetween during the laterstages of the filling process. The part of the cone pointing toward theinside of the sack should be of such an inside diameter that it fitssnugly and sealingly about the filling tube of the filling machine, butit should not be attached to the sack valve at any point at that end,since it must be capable of movement to accommodate the filling tubewithout rupturing the sack.

The sealing insert can be made of any material, such as a metal or aplastic, but it should be sufficiently resilient in the thickness usedto become distorted under the described stress, but return to itsorginal configuration when the stress is relieved. Suitable materialsinclude stainless steel, polyethylene, polypropylene, polyvinylchloride, polyamide, natural rubber, and synthetic rubbers. If thesealing insert is to be a part of the sack, it can also be made of thesame material as the sack, for example, plastic in the case of plasticfilm sacks, or paper in the case of paper sacks, but it may also be madeof any material that can be bonded or held in the sack, and is suitablefor the purpose.

FIG. 1 is a view in longitudinal section of a filling tube, sack valveand sealing insert in accordance with the invention.

FIG. 2 is a cross-sectional view taken along the lines 22 of FIG. 1.

FIG. 3 is a view in longitudinal section of another embodiment of sackvalve and sealing insert in accordance with the invention, provided withcircumferential ridges to improve the seal against the wall of the sackvalve.

The filling machine shown in FIGS. 1 and 2 is especially adapted forfilling particulate material such as cement into valve sacks. The hopper1 of the filling ma chine, within which the particulate material iscontained, is provided at its lower end with a turbine wheel 2, which isrotatable and which feeds material from the hopper into the filling tube3. The filling tube is of a narrow diameter, so as to extend through thesack valve 9 of a sack 4 to be filled with the particulate material inthe hopper.

A sealing insert in the form of a truncated cone 5 is mounted in a pressand sealing fit on the outside of filling tube 3. The narrow end 6 lieson a portion of lesser outside diameter 10 of the filling tube, tightlyembracing this portion of the tube. The end face 11 of the insert 5abuts and seals against a corresponding face 12 of a portion 13 of widerdiameter, at the nozzle 14 end of the filling tube 3.

The wide end 7 of the conical insert 5 is slightly (0.1 mm) wider thanthe inside diameter of the inner wall 8 of the sack valve 9, andconsequently fits snugly and sealingly against this wall. Thus, aircannot pass between the end 7 and the wall 8, nor can it pass betweenthe tube 3 and the inside wall of the narrow end 6 of the conical insert5.

The sealing insert is made of a hard but resilient material, such asrubber or polyethylene.

In operation, particulate material is fed from the hopper 1 by theturbine wheel 2 into and through the filling tube 3 into the openinterior of the sack 4. Tight sealing between the wide end 7 of theinsert 5 and the Wall 8 of the sack valve 9 prevents air from beingdrawn into the sack, as the sack becomes taut with the weight ofmaterial during the initial stages of the filling process. As the sackfills with material, however, the weight of material draws the sides ofthe sack downwardly, and this eventually results in deformation of thewide end of the cone 7, which opens a passage for air between the end 7and the inside wall 8, and allows the air (now, under pressure) insidethe sackto escape. Eventually the sack is filled, and the tube 3 and thesealing insert 5 can then be withdrawn, and the opening into the sackclosed.

In order to allow air within the sack to escape more easily at the endof the filling operation, the sealing insert can be designed with thelower part softer than the upper part. This can be done, for example, bymaking the walls of the narrow end thinner, or by grinding grooves intothe material at this end. If this is done, however, the grooves shouldbe inserted on the exterior of the material, to keep the inside of thenarrow end smooth enough to obtain good seal is obtained against thetube 3. It is also important that the outside periphery of the wide end7 of the cone be completely smooth, to obtain a good seal against theinner wall 8 of the sack valve 9. Thus, any grooving or reduction inthickness of the walls at this end should be on the inside.

In order to improve the seal against the wall 8 of the sack valvefurther, the sealing insert can be provided with circumferential ridges,so that a longitudinal crosssection would show one or moreprotuberances, as shown in FIG. 3. The sealing insert 15 of FIG. 3 isprovided with three circumferential ridges 16, 17, 18 sealing againstthe wall 8 of the sack valve. Due to the difference in space between theconical insert 15 and the inner wall 8 of the sack valve, the ridgesensure a good seal against the inner wall 8.

Having regard to the foregoing disclosure, the following is claimed asthe inventive and patentable embodiments thereof:

1. A sack-filling device for filling particulate material into sacksprovided with a sack valve without entrainment of air in the filledsack, permitting air within the sack to vent while preventing entry ofoutside air during the filling operation, comprising, in combination, asack-filling means smaller in external diameter than the inside diameterof the sack valve, defining an annular space between its outside walland the inside wall of the sack valve, and adapted to extend into thesack valve to feed particulate material into the sack; and a sealinginsert of resilient material in the form of a truncated cone attached tothe sack-filling means; the sealing insert being provided with ridgesrunning circumferentially about the insert, to improve sealing betweenthe sealing insert and the inside wall of the sack valve, having a wideend and a narrow end and having axial apertures only at the wide andnarrow ends, coaxially embracing the sack-filling means and disposedacross the annular space between the sack valve and the sackfillingmeans, sealing engaging in a secured and closed relationship the outsideof the sack-filling means at the narrow end, and sealingly engaging in aflexible relationship the inside of the sack valve at the wide end, tosubstantially close off the annular space, the sackfilling means havinga recessed portion on its exterior wall, and the sealing insert at itsnarrow end sealingly engaging the sack-filling means at the recess, theinsert being sufficiently resilient to flex away automatically from theinside wall of the sack valve and open the seal therewith for egress ofgas via the annular space from within the sack when under high gaspressure therewithin, or under stress applied to the insert by the sackunder the weight of particulate material filled therein.

2. A sack-filling device in accordance with claim 1, in which thesack-filling means is a tube.

3. A sack-filling device in accordance with claim 1, in which theresilient material is rubber.

4. A sack-filling device in accordance with claim 1, in which thesealing insert is attached to the sack-filling means at a narrow portionthereof, and is lodged in a recess therein to improve sealing therewith.

5. A sack-filling device in accordance with claim 4, in which thesealing insert surrounds and is sealingly attached .to the sack-fillingmeans.

1. A sack-filling device for filling particulate material into sacksprovided with a sack valve without entrainment of air in the filledsack, permitting air within the sack to vent while preventing entry ofoutside air during the filling operation, comprising, in combination, asack-filling means smaller in external diameter than the inside diameterof the sack valve, defining an annular space between its outside walland the inside wall of the sack valve, and adapted to extend into thesack valve to feed particulate material into the sack; and a sealinginsert of resilient material in the form of a truncated cone attached tothe sack-filling means; the sealing insert being provided with ridgesrunning circumferentially about the insert, to improve sealing betweenthe sealing insert and the inside wall of the sack valve, having a wideend and a narrow end and having axial apertures only at the wide andnarrow ends, coaxially embracing the sack-filling means and disposedacross the annular space between the sack valve and the sack-fillingmeans, sealing engaging in a secured and closed relationship the outsideof the sack-filling means at the narrow end, and sealingly engaging in aflexible relationship the inside of the sack valve at the wide end, tosubstantially close off the annular space, the sack-filling means havinga recessed portion on its exterior wall, and the sealing insert at itsnarrow end sealingly engaging the sack-filling means at the recess, theinsert being sufficiently resilient to flex away automatically from theinside wall of the sack valve and open the seal therewith for egress ofgas via the annular space from within the sack when under high gaspressure therewithin, or under stress applied to the insert by the sackunder the weight of particulate material filled therein.
 1. Asack-filling device for filling particulate material into sacks providedwith a sack valve without entrainment of air in the filled sack,permitting air within the sack to vent while preventing entry of outsideair during the filling operation, comprising, in combination, asack-filling means smaller in external diameter than the inside diameterof the sack valve, defining an annular space between its outside walland the inside wall of the sack valve, and adapted to extend into thesack valve to feed particulate material into the sack; and a sealinginsert of resilient material in the form of a truncated cone attached tothe sack-filling means; the sealing insert being provided with ridgesrunning circumferentially about the insert, to improve sealing betweenthe sealing insert and the inside wall of the sack valve, having a wideend and a narrow end and having axial apertures only at the wide andnarrow ends, coaxially embracing the sack-filling means and disposedacross the annular space between the sack valve and the sack-fillingmeans, sealing engaging in a secured and closed relationship the outsideof the sack-filling means at the narrow end, and sealingly engaging in aflexible relationship the inside of the sack valve at the wide end, tosubstantially close off the annular space, the sackfilling means havinga recessed portion on its exterior wall, and the sealing insert at itsnarrow end sealingly engaging the sackfilling means at the recess, theinsert being sufficiently resilient to flex away automatically from theinside wall of the sack valve and open the seal therewith for egress ofgas via the annular space from within the sack when under high gaspressure therewithin, or under stress applied to the insert by the sackunder the weight of particulate material filled therein.
 2. Asack-filling device in accordance with claim 1, in which thesack-filling means is a tube.
 3. A sack-filling device in accordancewith claim 1, in which the resilient material is rubber.
 4. Asack-filling device in accordance with claim 1, in which the sealinginsert is attached to the sack-filling means at a narrow portionthereof, and is lodged in a recess therein to improve sealing therewith.